Pakistan's military has arrested more than 100 suspects in their five-day assault on al-Qaida fighters holed up in mud fortresses along the border. Those detained included foreigners and the local Pashtun tribesmen who have been sheltering them, said Lieutenant General Safdar Husayn, the military commander who is in charge of the sweep. Husayn said 400 to 500 fighters were believed to still be fighting from within heavily fortified compounds, using mortars, AK-47s, rockets and hand-grenades in a face-off with troops. "These people have been here for a long, long time. They are extremely professional fighters," he said. "They have tremendous patience before they open fire." "They are taking us from every direction whenever our troops have moved in and we are not knowing if the locals are with us," he added. "With an undefined target like this, it is practically chasing shadows." The military showed journalists 40 prisoners, all blindfolded and with their hands tied, who were sitting under heavy guard in the back of a military truck in Wana, the main town in the tribal South Waziristan region, where the battle was raging. The army also displayed the body of one suspected fighter wrapped in a white blanket. Husayn said troops were convinced the compounds held a "high-value" target, but he said they had no confirmation the man was al-Zawahiri. **Bin Laden 'fine'*** Meanwhile, al-Qaida leader Usama bin Ladin and al-Zawahiri, are reported to be safe. "Muslims of the world - don't worry about them, these two guests are fine", a Taliban spokesman Abd Al-Samad, told AP by telephone. At least 43 people have already been killed in the assault which began early last week, in South Waziristan - a forbidding tribal region, with several mud fortresses, near the border with Afghanistan. "The operation is on", Pakistani army spokesman Major General Shaukat Sultan said on Saturday. He reported no arrests of any senior al-Qaida member, backing the Taliban spokesman's comments. On Friday, Sultan said the Pakistani forces were joined by "a dozen or so" American intelligence agents in the ongoing offensive. US satellites, predator drones and other surveillance equipment hovered overhead. An estimated 300 to 400 fighters - a mix of foreigners and Pakistani tribesmen - were facing off against the military in several villages including Kaloosha, Azam Warsak and Shin Warsak, according to Sultan. Sultan said authorities' intelligence assessment was that a high-level fugitive was among the fighters, but that he had not been seen and it was unclear whether it was al-Zawahiri. "The type of resistance, the type of preparation of their defensive positions, the hardened fortresses they have made means we can assume that there could probably be some high-value target there," Sultan said. **PHOTO CAPTION*** A Pakistani military official guards a captured man in Wana, Pakistan on March 20, 2004. (Faisal Mahmood/Reuters)